What do you call a machine learning system that keeps on learning?
There are several terms or expressions related to such systems, such as online learning, incremental learning, continuous learning, continual learning, and lifelong learning. They are sometimes used interchangeably, but some of them have slightly different meanings. For example, online learning does not need to be incremental, which refers to algorithms that attempt not to forget previously learned information.

The opposite of online is offline. However, the expression batch learning is sometimes used as an antonym for online learning.